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Information message about the earthquake in Afghanistan (Hindu Kush) on March 25, 2002

On March 25, 2002 destructive earthquake has happened in the North of Afghanistan. It occured at 17:56 Moscow time (14:56 GMT). This earthquake was felt on the vast territory of Central Asia.

Parameters of the earthquake have been determined in the Alert Service (AS) of Information Processing Center (IPC) of Geophysical Survey of RAS in Obninsk with station data obtained from digital and analog seismic stations of Russia, countries of CIS and from abroad. Alert message on this earthquake has been delivered in 50 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).

Preliminary processing has been done with data from 15 stations, accurate processing - with data 25 stations.

Figure 1 shows fragments of records with vertical components (BHZ) from digital stations, which were obtained by IPC in a near to real time mode: Borovoe (delta 17 degrees), Arti (delta 21 градус), Talaya (delta 29 degrees), Obninsk (delta 29 degrees), Lovozero (delta 37 degrees). Figure 2 shows vertical components (BHZ) from digital stations YAK (delta 45 degrees), Tiksi (delta 47 degrees), South-Sahalin (delta 54 градуса), Magadan (delta 56 degrees), Bilibino (delta 60 degrees). Represented wave picture is typical for the crust earthquakes: presence of initial long period vibration and distinct surface waves.

Figure 1

Figure 2

IPC GS RAS also has obtained information with parameters of this event from some seismological centers, these data are given in table 1:

Table 1

NN	Time in origin h-min-s (GMT)	Lat degr.	Lon degr.	Depth km	N s/st	Ms/ N	mb/ N	I0 calc	GAP	Center
1	14-56-33.30	35	69	10	25	6.00/18	5.90/15	7-8		IPC GS RAS (accurate)
2	14-56-37.3	36	69	33	15	6.0/10	5.8/10	6.5-7		IPC GS RAS (preliminary)
3	14-56-38.1	36	69	33	150	5.9-6.2				CSEM
4	14-56-33.3	35	69	8	72	6.3/55	6.0/30			NEIC

IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences

CSEM - European - Mediterranean seismological center

NEIC - National Earthquakes Information Center of US Geological Service

Epicenter

Epicenter of this earthquake was located in 135 km to the South-West from the recent earthquake of this region which happened on March 3. Both events occured in highly active seismic region, on the border of two plates – Eurasian and Indian. Numerous earthquakes happen here with origins both within the Earth's crust and at the depths up to 330 km. Destructions from the earthquake on March 25 were much more serious than from the earthquake on March 3, however the first event had less magnitude and its degenerated energy was 100 times less than energy from the earthquake on March 3. However the origin place on March 25 was located in the upper part of Mantle at the small depth (8-10 km), thus the big destructions were observed. Energy from surface earthquakes is released closer to the buildings giving stronger vibrations in comparison with earthquakes at the big depths inside the Earth.

Macroseismic manifestations

The earthquake has happened in the night between March 25 and 26 in mountains of highly seismic active region of Hindu Kushа, this is 170 km to the North from Afghanistan capital Kabul. Strong underground shocks were felt in the Northern Afghanistan: in towns Kabul, Mazar-I-sharif; in Pakistan: Islamabad, Peshevar; in Tajikistan: Dushanbe – intensity 3 - 4. From preliminary data by 26.03 as a result of this natural disaster 2 thousand people were killed, nearly 4 thousand were injured, more than 10 thousand Afghan residents became homeless, many people stay in the streets threatened to go inside not broken houses. Many of them are in the desert near desolated living places without meals and water. Town Nahrin in Baglan province was totally desolated, serious destructions are observed in neighboring settlement Burka. This earthquake was accompanied with numerous aftershocks lasting within the whole night. In period between March 25 and 27 there were registered 9 undeground shocks in the same Northern region with magnitudes 4 and higher. New undeground shocks increase the number of victims. Information about this earthquake is presented on Information server of National Earthquakes Information Center of US Geological Survey (NEIC). Afghan Government sent message to the World community with help request. United Nations sent humanitarian aid to the disastrous regions, including tents, blankets, food and medicine. Russia sent two planes to Kabul with humanitarian cargo.

Focal mechanism and seismic moment of the earthquake

Solutions of focal mechanism for the earthquake's origin were calculated with TMC method in different centers - National Earthquake Information Center (NEIC), HARVARD (USA), they are presented in table 2 and shown on fig. 3-4. Focal mechanisms of the Earthquake on March 25, 2002 from data of NEIC (fig.3), HARVARD (fig.4). As it is seen, solutions obtained by different centers are close to each other. Both nodal planes have almost meridional spread direction, type of motion along both planes – thrust. Motion in origin was under the action of prevailing compression strengths oriented in latitudinal direction. Value of seismic moment Мо calculated from Р-wave spectra in Obninsk made 1.5*10**25 D*CM. Values of seismic moment Мо from data of NEIC and HARVARD are close to the value determined in Obninsk and made 1.2*10**25 D*CM and 1.5*10**25 D*CM respectively. Value of moment magnitude determined in Obninsk made Mw=6.1 , NEIC - Mw=6.0, HARVARD - Mw=6.1 .

Table 2

Axes of main strengths						Nodal planes						Center
T		P		N		NP1			NP2
Pl	Azm	Pl	Azm	Pl	Azm	Stk	Dp	Slip	Stk	Dp	Slip
82	184	1	278	8	9	0	45	78	197	46	102	NEIC
62	186	2	281	28	12	345	49	52	215	54	125	HARVARD

NEIC - National Earthquakes Information Center of US Geological Service

HARVARD - Harvard Geophysical Center (USA)

Figure 3

Figure 4